Shotgun choke



Nov. 10, 1964 F. A. PACHMAYR 3,156,050

SHOTGUN CHOKE Filed Dec. 26, 1962 10 a2 l2a I2 e m/z J4. flCl-IMH we I NVEN TOR.

United States Patent "ice 3,156,060 SHOTGUN CHOKE Frank A. Pachmayr, Los Angeles, Calif, assignor to Pachmayr Gun Works, Inc, Los Angeles, Calif, a corporation of California Filed Dec. 26, 1962, Ser. No. 247,080 Claims. (Cl. 42-79) This invention has to do with improvements in shotgun variable chokes, i.e., shot pattern control devices applicable to the gun barrel and radially adjustable to vary the pattern of shot discharged through the device.

More particularly, the invention is concerned with improvements in shotgun chokes of the type comprising a body applicable at its rear to the gun barrel, and having associated therewith, e.g., as by integral formation, a forward section split longitudinally at circularly spaced intervals from the front discharge end of the sections to render the sections radially expandable and contractable for shot pattern control. Such radial variation results from rotation of a surrounding sleeve having wedge engagement with the body section within its split length. The shot controlling effect results from axial variations of the section bore wall angularity in relation to the body axis.

Shot pattern control devices as thus broadly characterized, are well known in the art. In some instances the bore variation has been changed in the angularity of an essentially single taper, while in other instances different lengths of the bore wall have had different angular relations to the bore axis and the effect of the adjustment has been to vary the relationships between those angularities, as well as to the bore axis.

The present invention, being in the latter category, has for its object to provide for a particular and novel relation between different bore length angularities, which permit more effective shot pattern control primarily in two conditions; first, when the pattern is to be relatively scattered, and second, when the pattern is more concentrated. These requirements are met by simple relationships between the forward and rear extents of the radially variable bore wall in the fully expanded and fully contracted conditions of the split body section.

Specifically contemplated are bore surface angularities such that in the expanded condition of the choke, the rear bore length wall will be straight, i.e., in substantial parallelism with the body axis and the forward length will progressively enlarge, thus to give a relatively enlarged pattern to be shot initially under straight wall control. Upon adjustment from radially enlarged to contracted condition of the split body section, the relation of such forward and rear bore surfaces reverses in that the rear extent is deflected to converge forwardly and the front section becomes straight, i.e., substantially parallel with the body axis. The result then is that the straight front section is fed with shot convergently directed by the tapering rear section.

The invention further contemplates interengaging wedge means on the split body section and surrounding sleeve, so positioned axially of the body to accurately support and predetermine the bore angular relations discussed in the foregoing.

All these, as well as additional features and objects, will be more fully understood from the following detailed description of an illustrative embodiment shown by the accompanying drawing in which:

FIG. 1 is a view showing the choke device partially in longitudinal section;

FIG. 2 is a fragmentary enlarged section showing the device in one condition of adjustment;

FIG. 3 is a view similar to FIG. 2 showing the device in a reversed condition of adjustment; and

3,1553% Patented Nov. 10, 1964 FIG. 4 is a cross section on line 44 of FIG. 1.

The choke device, generally indicated at 10, is shown to be mounted on the end of a shotgun barrel 11, it being understood that the mode of attachment of the device to the barrel, which constitutes no part of the present invention, may be in accordance with any of the various known types and designs of mountings. The device is shown to comprise a tubular metallic, e.g. steel, body 12, preferably of one-piece construction, having a forward radially adjustable extent 12a, and a rearward portion 12!), the wall of which is slotted to provide an appropriate number and arrangement of apertures or slots 13 for venting discharge gases in advance of the shot entry to the forward extent of the body.

Referring particularly to FIGS. 2 and 3, the forward body extent 12a is slotted at 14 rearwardly from the forward end of the body throughout a longitudinal extent sufficient to accommodate and permit the bore angular extents and variations later described, the slots 14 being circularly arranged at uniformly spaced intervals, as shown in FIG. 4. As will be apparent, the arcuate section, finger-like extents of the body between the slots are radially expansible and contractable by reason of the slotted configuration and the resilient elasticity of the body.

Each of the body fingers or segments 15 between the slots is shown to have a terminal angular and arcuate wedge surface 16, a forward intermediate arcuate lug 17 with a correspondly angled arcuate wedge surface 13, and a rearwardly intermediate rounded surface, wedgeacting arcuate lug 19.

Radial variation of the slotted body extent 12a is effected by a surrounding manually rotatable sleeve 2% having longitudinal hand grip knurlings 4t and threaded at 41 to the body for rotation and consequent axial movement thereon. Within its forward end, the sleeve has an annular wedge surface 21 engaging with and corresponding in angularity to the body surface 16; a forward intermediate annular surface 22 engaging with and corresponding in angularity to the body surface 18, and a rearward annular angular surface 23 engageable by the body lugs 19. Fitted within annular recess 24 in the body is split snap ring 25, one end of which, projecting through opening 26, is defiectably engageable with the irregularities produced by the slots 14 to provide a detenting action which releasably retains the sleeve in rotative positions of adjustment.

The forward and rear extents 27 and 281 of the bore wall defined within the slotted extent of the body, have predetermined individual and relative angularities in order to achieve alternate selective relative angularities of the bore extents, as and for the purposes previously discussed. In the FIG. 2 condition of rotative adjustment of the sleeve 20, the relationship of the angularities of bore lengths 27 with 28 is such as to produce initial convergence and then straight direction of the shot discharged through the body. Here the wall of the rearward bore extent 28 is shown to converge at 30 toward the forward length 27 (generally delineated by line 31), whereas the wall section 27 is shown at 32 to be straight, i.e., parallel with the body axis. Maintenance of the bore lengths in the described and illustrated configurations and relationship, is positively supported and assured by the interengaging wedge surfaces 16-21, 18-22 and 2923, the support by 18-22 being at the juncture of the bore lengths 27 and 28, and the support at 19-23 being centrally intermediate the rear extent 28. In this manner, it is possible to maintain extreme accuracy in the angular relations of the bore extents and the consequent shot control.

By rotation of sleeve 20 a full turn to the FIG. 3 position, the wedge pressures are relieved to the extent that the inter-groove segments expand by their resiliency to produce a reverse relative angularity of the bore lengths 27 and 28. Here the bore extent 27 progressively enlarges or flares forwardly from its rear approximately at 31, and the rear Wall extent 30 assumes a straight configuration, i.e. parallelism with the body axis, the described relationships again being positively maintained by the three sets of interengaged body and sleeve wedge surfaces.

As will be understood by those familiar with the art, when it is desired to discharge the shot in a more concentrated pattern, the sleeve is adjusted to the FIG. 2 position, wherein the shot initially is gathered by the front taper at30, and the pattern is maintained in a straight course by the axially parallel wall at 32. When it is desired to discharge the shot in a relative scatter pattern, the sleeve is adjusted to the FIG. 3 position wherein the shot initially gains straight alignmentby the axially parallel wall 30, and then is allowed to spread by reason of the front extent divergence at 32.

I claim:

1. A shotgun choke comprising a tubular body applicable at its rear to a gun barrel and split from its front end rearwardly and at circular intervals to form a radially expansible and contractable shot pattern control section, said section having within its split length a bore having an axially inner extent the wallof which in the expanded condition of the section being in substantially straight parallelism with the body axis, and a forward wall ex= tent which progressively enlarges to the discharge end of the section, said bore wall extents being angularly related so that in the radially contracted condition of the body said inner extent of the bore wall progressively tapers toward said forward extent the Wall of which then is in substantially straight parallelism with the body axis, a sleeve rotatable about said split section of the body, and interengaging wedge means on said section and sleeve operable by rotation of the sleeve to radially deflect the section between said expanded and contracted conditions.

2. A choke according to claim 1, in which said wedge means comprise interengaging wedge surfaces on the sleeve and section at the forward end of the section and second and third essentially annular interengaging pairs of axially spaced wedge surfaces on the sleeve and section within the split length of the section.

3. A choke according to claim 2, in which said second pair of wedge surfaces are located at the inner end of said forward extent of the bore wall.

4. A choke according to claim 3, in which said third pair of wedge surfaces are located intermediate the ends of said inner straight extent of the bore wall.

5. A choke according to claim 4, in which said body is one piece from its front discharge end to its rear barrel attachment end, the body being slotted to vent gases rearwardly of said split section.

No references cited. 

1. A SHOTGUN CHOKE COMPRISING A TUBULAR BODY APPLICABLE AT ITS REAR TO A GUN BARREL AND SPLIT FROM ITS FRONT END REARWARDLY AND AT CIRCULAR INTERVALS TO FORM A RADIALLY EXPANSIBLE AND CONTRACTABLE SHOT PATTERN CONTROL SECTION, SAID SECTION HAVING WITHIN ITS SPLIT LENGTH A BORE HAVING AN AXIALLY INNER EXTENT THE WALL OF WHICH IN THE EXPANDED CONDITION OF THE SECTION BEING IN SUBSTANTIALLY STRAIGHT PARALLELISM WITH THE BODY AXIS, AND A FORWARD WALL EXTENT WHICH PROGRESSIVELY ENLARGES TO THE DISCHARGE END OF THE SECTION, SAID BORE WALL EXTENTS BEING ANGULARLY RELATED SO THAT IN THE RADIALLY CONTRACTED CONDITION OF THE BODY SAID INNER EXTENT OF THE BORE WALL PROGRESSIVELY TAPERS TOWARD SAID FORWARD EXTENT THE WALL OF WHICH THEN IS IN SUBSTANTIALLY STRAIGHT PARALLELISM WITH THE BODY AXIS, A SLEEVE ROTATABLE ABOUT SAID SPLIT SECTION OF THE BODY, AND INTERENGAGING WEDGE MEANS ON SAID SECTION AND SLEEVE OPERABLE BY ROTATION OF THE SLEEVE TO RADIALLY DEFLECT THE SECTION BETWEEN SAID EXPANDED AND CONTRACTED CONDITIONS. 